Flame equalizer for two or three burner camp stoves

ABSTRACT

A flame equalizer for use in a two or three burner camp stove of the type having a primary burner with a series connection for fuel flow to the other burners associated therewith, the flame equalizer being contained within the primary burner to provide a variable restriction for the gas flow from the plenum to the primary burner surface to divert an equal flow of gas to the secondary burners as the secondary burners are actuated.

United States Patent 91 Amos [ FLAME EQUALIZER FOR TWO OR THREE BURNER CAMP STOVES [75] Inventor: James H. Amos, Mission Hills, Calif.

[73] Assignee: Minnesota Mining and Manufacturing Company [22] Filed: Oct. 14, 1971 21 Appl. No.: 189,357

[52] US. Cl 126/38, 431/234 [51] Int. Cl F24c 15/10, F23d 23/00 [58] Field of Search 126/38, 44, 39 N;

[56] References Cited UNITED STATES PATENTS 3,7l4,938 2/1973 Spotts 126/38 Jan. 8, 1974 5/1928 Thatcher 431/234 3/1964 Green 431/234 Primary Examiner-William F. ODea Assistant Examiner-Harold Joyce Attorney-John G. Mesaros ABSTRACT A flame equalizer for use in a two or three burner camp stove of the type having a primary burner with a series connection for fuel flow to the other burners associated therewith, the flame equalizer being contained within the primary burner to provide a variable restriction for the gas flow from the plenum to the primary burner surface to divert an equal flow of gas to the secondary burners as the secondary burners are actuated.

10 Claims, 4 Drawing Figures PMENTEBJAN 85974 Fig.4

JAMES H OS INVENTOR FLAME EQUALIZER FOR TWO OR THREE BURNER CAMP STOVES BACKGROUND OF THE INVENTION This invention relates to an improvement for a two or three burner camp stove which is fed fuel consisting of a mixture of air and liquid gasoline to two or more burners in series. In such camp stoves the fuel is fed from a bottle through a pipe disposed in thermal contact with the flame of the primary burner, which pipe acts as a vapor generator. The vapor is then mixed with air in a mixing chamber and carried to the primary burner plenum- From there the vapor and air mixture is carried by a duct communicating with the plenum through a valve to the secondary burner. However, there has been here an operating deficiency that provides a flame at the primary burner, that is, the burner closest to the fuel supply, which flame is much higher than that attainable at any of the secondary burners. The secondary burners are very limited in their usefulness and the camp stove cannot heat a large griddle covering the two burners evenly. This difference in flame intensity is due to the design of the gas ducting system which directs the entire gas input, first to the primary burner plenum and then diverts it from there for one or more secondary burners.

SUMMARY OF THE INVENTION In accordance with this invention a variable selfadjusting restriction is provided within the primary burner intermediate the plenum and the burner surface. In one embodiment the burner is provided with a centrally disposed shaft having an aluminum discshaped member with an aperture therein adapted for motion within the burner in the direction of the shaft. In the normal position of the disc-shaped member with no gas or fuel applied to the burner the member rests on shoulders within the burner. As fuel is supplied to the burner the member rises a height dependent upon the pressure of the entering fuel to permit full usage of the primary burner. As one or more secondary burners are ignited the pressure in the primary burner decreases, thereby permitting the disc member to drop back toward or on the shoulders to provide pressure against the flow of fuel into the primary burner and secondary burners. The aperture within the disc member is generally slightly larger than the diameter of the shaft on which it rides to permit the flow of fuel therethrough to the primary burner surface. The weight and configuration of the disc member are predetermined for optimum flame equalization. In a three burner configuration the primary burner and the immediately adjacent secondary burner can both be provided with the disc members, the weight of the disc member for the secondary burner being slightly less than the weight of the disc member for the primary burner.

' Accordingly, it is an object of this invention to provide a new and improved flame equalizer for two or three burner camp stoves.

It is another object of this invention to provide a new and improved flame equalizer for two or three burner camp stoves for modification of existing camp stoves.

It is a further object of this invention to provide a new and improved flame equalizer for two or three burner camp stoves which is economical to produce and to install.

It is still another object of this invention to provide a-new and improved flame equalizer which is operable by the pressure of the incoming fuel.

DESCRIPTION OF THE DRAWINGS Other objects, features and advantages of the present invention will become apparent from the following detailed description when considered with the accompanying drawings, in which:

FIG. 1 is a perspective view of a two burner camp stove for use with the invention;

FIG. 2 is a cross-sectional view taken along lineII-II of FIG. 1 showing details of the invention;

FIG. 3 is a cross-sectional view taken along line III- III of FIG. 2; and

FIG. 4 shows a washer and spacer assembly for use in the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and particularly to FIG. 1, there is shown a two burner camp stove l0 having a fuel supply contained in a bottle 12 for feeding fuel through vapor generator pipe 14 through a mixer 16 to a primary burner 18 and if desired to a secondary burner 20 through duct 22. The primary burner 18 is usually fed fuel by actuation of a knob 24 on fuel bottle 12 which controls the flow of fuel through pipe 14 to primary burner 18. A secondary burner 20 is fed fuel only after primary burner 18 is ignited by means of a valve such as a valve 26 (see FIG. 2) contained within the duct 22. In any event, there is a fuel flow control device intermediate the two burners and so disposed that there is a series gas flow from the primary burner to the secondary burner whereby the pressure of the gas at the secondary burner is less than that at the primary burner due to the additional distance therebetween.

As better illustrated in FIG. 2, the pipe 14 is a vapor generator and is in thermal contact with the primary burner 18 to assist in vaporizing the fuel being transmitted therethrough when the burner is ignited. The vapor then goes into mixing chamber 16 where it is mixed with air, the mixture communicating with the plenum 26 of primary burner 18 by means of aperture 18. In accordance with the invention a self-adjusting variable restriction device is provided intermediate the plenum 26 and the burner surface 30 which is an annular member having a plurality of apertures therein in a radial direction to permit the escape of gas to a dish-shaped member 34 surrounding the burner surface 30, the

outer edges of member 34 being directed upwardly. A burner plate member 36 is provided to retain burner surface 30 and dishmember 34 in position with respect to an enlarged portion 38 of plenum 26. The burner plate 36 has a centrally located aperture through which is inserted a screw member 40 engaging an aligned stud 40 affixed, for example, by welding to the bottom of the plenum 26.

In existing camp stoves, a variable restriction device such as the washer and spacer assembly shown in FIG. 4 can be added. The washer 44 is generally disc shaped with a centrally located aperture 46 while the spacer 48 is generally cylindrical with a centrally disposed aperture 50 therethrough. The spacer 48 is positioned coaxial with stud 42 and the screw 40 is inserted therethrough. The washer 44 is of sufficient diameter to rest on shoulder 52 at the enlarged portion 38 of plenum 26. While the burner is round in cross section, the shoulder 52 is square'because of the fabrication techniques employed, and the outer diameter of washer 44 is, smaller than the diagonal of the shoulder 52 to create apertures adjacent the corners. The aperture 46 is of a slightly larger diameter than the spacer 48 for reasons which will herein after be discussed. In FIG. 2 the solid line washer 44 is shown in its normal position, that is, without fuel being supplied. In addition to the passage space between the washer 44 and spacer 48 there is also fuel passage space adjacent the four comers 53 of shoulder 52. (See also FIG. 3.) As fuel is supplied through aperture 28 the washer 44 uniformly rises due to the uniform pressure of the gas thereagainst. The washer 44 has a weight which is sufficient to permit it to rise while being heavy enough to provide pressure against the flow of the incoming fuel. The washer 44 can be made of any suitable material such as iron, steel, aluminum or even non-metallic materials such as fiber or plastic, the only requirement being that the material have sufficient resistance to the temperature of the sur rounding parts which in no event would be as great as the flame temperature. Also, obviously, the material employed for washer 44 must have sufficient weight to accomplish the intended result, that is, it must be light enough to rise and heavy enough to settle and impose proper restriction on fuel flow to primary burner 18 when secondary burner 20 is used.

When the valve 26 is open to permit the flow of fuel through duct 22 to plenum 54 of secondary burner 20 (the dotted line position of damper 26), the pressure within plenum 26 is reduced, the washer 44 helping to assist in the reduction of the pressure and consequently the flow of fuel through burner surface 30. The washer 44 then returns to the position shown in solid lines in FIG. 2, that is, resting on shoulder 52 providing maximum restriction for gas flow to the primary burner 18. By proper selection of weight for washer 44, the flame at the burner surfaces of the primary and secondary burners 18 and 20, respectively, can be equalized.

In a three burner configuration with a third burner in series with the second burner, the secondary burner 20 can also have a self-adjusting variable restriction therein in accordance with the invention. In such a case the washer members 44 would not be identical inasmuch as it would be required that the washer 44 for the primary burner 18 have a heavier weight than a similar washer 44 coacting with the secondary burner 20 to provide flame equalization to a third burner (not shown). On the other hand, if the second and third burners are fed in parallel from the plenum 26 or on opposite sides of plenum 26 then only one variable restriction would be required at the primary burner 18 in order to equalize the flame of all three burners in actual usage.

The embodiment shown is readily adaptable as a modification of existing two burner camp stoves by the utilization of the washer 44 and spacer 48. It is not intended, however, that the invention be limited thereby inasmuch as the same can be accomplished by providing a washer cooperating with a screw member of smaller diameter than the aperture 46 therein, the shank of the screw member having smooth surfaces in the range of effective use adjacent the aperture 46. Alternatively, the washer 44 can be perforated or have patterns therein around the center aperture 46 to permit gas flow therethrough while having its weight operate against the pressure of the incoming fuel. Additionally, the washer 44 can have radially-extending flutes to permit the flow of gas through apertures formed between the flutes and the shoulder 52 of the enlarged portion 38 of plenum 26. Alternatively, the washer 44 can be rectangular or any other configuration as can be the aperture 46 to cooperate with a shaft of similar configuration.

While there has been shown and described a preferred embodiment of the invention, it is to be understood that various other modifications and adaptions may be made within the spirit and scope of the invention.

What is claimed is:

1. In a portable gas stove the combination comprising:

a primary burner having a plenum chamber;

means for introducing pressurized fuel into said plenum chamber;

at least one secondary burner having duct means cooperating with said plenum chamber to permit the flow of fuel to said secondary burner;

valve means for controlling the flow of fuel to said secondary burner only when fuel is present in said plenum chamber; and

variable restriction means within said primary burner and being actuable by the fuel in the plenum chamber to operate against the pressure of said fuel, said restriction means operating against the pressure sufficiently when said valve means are opened to provide substantially equal flame at said primary and secondary burners when both are operating.

2. The combination according to claim I wherein said plenum chamber has an enlarged portion intermediate said plenum chamber and the primary burner, the enlarged portion forming a shoulder, and the variable restriction device includes a shaft member centrally disposed with respect to said shoulders and a washer member having a diameter sufficient to rest on said shoulder and a centrally located aperture having a diameter larger than said shaft member for location thereon.

3. The combination according to claim 2 wherein said washer has a predetermined weight sufficient to permit it to rise off the shoulder under the influence of the pressurized fuel when the primary burner is operating and sufficient to permit it to rest on the shoulder when said secondary burner is operating.

4. The combination according to claim 1 wherein said variable restriction device is actuable by the fuel pressure between a first position to provide maximum restriction at lower fuel pressures and a second position to provide minimum restriction at higher fuel pressures within the primary burner.

5. The combination according to claim 4 wherein at least a portion of said variable restriction device is physically displaced within said primary burner as the pressure of the fuel increases, said portion having sufficient weight to urge against the fuel flow.

6. In a portable gas stove for use with pressurized fuel and having a primary burner with a plenum containing an enlarged shoulder portion, a secondary burner having duct means cooperating with the plenum, and valve means within said duct means for providing fuel to the secondary burner only when fuel is present in the plenum, the combination comprising:

shaft means axially located within the primary burner; and a washer member having an aperture for loosely engaging said shaft means, said washer member being so configured to rest on said shoulder portion and provide a plurality of apertures between the periphery thereof and said shoulder portion, said washer member having a weight sufi'icient to permit said member to rise under the pressure of the fuel when the primary burner is actuated and to rest on the shoulder portion when the valve means is operated to actuate the second burner. 7. The combination according to claim 6 wherein the shoulder portion has a square configuration and said washer member is circular with a diameter larger than a side of the square but smaller than the diagonal thereof to provide four apertures adjacent the corners.

8. The combination according to claim 7 wherein the shaft means has a circular cross section and the aperture in the washer member is circular with a diameter slightly larger than the shaft means to provide a fuel flow passage therebetween.

9. The combination according to claim 8 wherein the washer member is made of aluminum.

10. The combination according to claim 9 wherein the shaft means has a smooth outer surface in the range of movement of said washer member.

Patent No.. 3,7 3, 5 Dated Januarl'8, 1 974 Inventor) James H. Amos It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet cancel "[73] Assignee: Minnesota Mining and Manufacturing Company" Signed and sealed this 5th day of March 1974.f

(SEAL) Attest:

EDWARD M.FLE TCHER5JR. MARSHALLDANM i a Attesting Officer. rcommlss-ioner ofvP-ate'nt 

1. In a portable gas stove the combination comprising: a primary burner having a plenum chamber; means for introducing pressurized fuel into said plenum chamber; at least one secondary burner having duct means cooperating with said plenum chamber to permit the flow of fuel to said secondary burner; valve means for controlling the flow of fuel to said secondary burner only when fuel is present in said Plenum chamber; and variable restriction means within said primary burner and being actuable by the fuel in the plenum chamber to operate against the pressure of said fuel, said restriction means operating against the pressure sufficiently when said valve means are opened to provide substantially equal flame at said primary and secondary burners when both are operating.
 2. The combination according to claim 1 wherein said plenum chamber has an enlarged portion intermediate said plenum chamber and the primary burner, the enlarged portion forming a shoulder, and the variable restriction device includes a shaft member centrally disposed with respect to said shoulders and a washer member having a diameter sufficient to rest on said shoulder and a centrally located aperture having a diameter larger than said shaft member for location thereon.
 3. The combination according to claim 2 wherein said washer has a predetermined weight sufficient to permit it to rise off the shoulder under the influence of the pressurized fuel when the primary burner is operating and sufficient to permit it to rest on the shoulder when said secondary burner is operating.
 4. The combination according to claim 1 wherein said variable restriction device is actuable by the fuel pressure between a first position to provide maximum restriction at lower fuel pressures and a second position to provide minimum restriction at higher fuel pressures within the primary burner.
 5. The combination according to claim 4 wherein at least a portion of said variable restriction device is physically displaced within said primary burner as the pressure of the fuel increases, said portion having sufficient weight to urge against the fuel flow.
 6. In a portable gas stove for use with pressurized fuel and having a primary burner with a plenum containing an enlarged shoulder portion, a secondary burner having duct means cooperating with the plenum, and valve means within said duct means for providing fuel to the secondary burner only when fuel is present in the plenum, the combination comprising: shaft means axially located within the primary burner; and a washer member having an aperture for loosely engaging said shaft means, said washer member being so configured to rest on said shoulder portion and provide a plurality of apertures between the periphery thereof and said shoulder portion, said washer member having a weight sufficient to permit said member to rise under the pressure of the fuel when the primary burner is actuated and to rest on the shoulder portion when the valve means is operated to actuate the second burner.
 7. The combination according to claim 6 wherein the shoulder portion has a square configuration and said washer member is circular with a diameter larger than a side of the square but smaller than the diagonal thereof to provide four apertures adjacent the corners.
 8. The combination according to claim 7 wherein the shaft means has a circular cross section and the aperture in the washer member is circular with a diameter slightly larger than the shaft means to provide a fuel flow passage therebetween.
 9. The combination according to claim 8 wherein the washer member is made of aluminum.
 10. The combination according to claim 9 wherein the shaft means has a smooth outer surface in the range of movement of said washer member. 